Solar Powered Cars - in our Future?

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"So when you consider how much energy you get out of any bio-fuel, you must subtract off what you put in. "

The cost of Bio-fuels include all those energy put in. America's Corn based Ethanol yields roughly 1.3 units for every unit in.Brazil's Cane based Ethanol yields even more and that is why that country have an extensive usage of that fuel. This year the Flex Fuel Vehicles are expected to capture 50 % of their market.

Also please note that Oil does not come in if you put a straw. In USA, we have to go more than a kilometer depth to get it, infact if they drill 1000 wells, they get Oil in only 500 wells.The amount of energy that is needed to drill will be enormous.

Development around solar energy hasn&#146;t stayed put since the 1980s. A lot of new technologies have been developed, are being used, and are being developed. And believe it or not, some companies are using solar cell panels on the roof of their manufacturing plants to cut down production costs by lowering electricity costs purchased from traditional grids.

The efficiency has gone up but it is nowhere close to where it could be in the future. And cost has gone down. Honda announced its iteration of solar cell technology in 2002 with a 40% reduction in manufacturing costs (and is using its CIGS solar cell panel to partly supply power its manufacturing facilities, as well as in hydrogen extraction from water (HES/HES-II). Here is an excerpt:

Solar powered cars are great food for thought for those whose thought processes are unencumbered by the realities of physics and the earth's astronomical relation to the sun. It's nice to dream of technological breakthroughs that will overcome present limitations, but there are natural limiting conditions that no technology can alter.

The Sun's power reaches the Earth's surface at a density of approximately 1.4kW/sq Meter. This is the maximum available on a surface normal to the Sun and may be diminished by atmospheric conditions. Present silicon PV cells operate at around 10-12% efficiency, but suppose a wondrous technology were developed to convert all of the available solar energy to electrical energy and suppose further that the vehicles' electrical-mechanical conversion efficiency was 100%, is there enough power from the Sun to drive such a vehicle?

Consider first, how much power does a vehicle require? This is not a simple question since the answer varies with the size, shape and mass of the vehicle and how it is to be operated. For an alternative to succeed in the market, however, it must be competitive with the vehicles that it seeks to replace so let's assume a vehicle similar to present 4 door sedans as a "mainstream" model. That suggests a vehicle of around 3200lbm, 0.32cd, 24sq-ft frontal area and a plan area of about 100sq-ft. We must assume that some form of energy storage is available to handle peak requirements (acceleration, hill climbing) since the 150hp+ of present vehicles obviously is not available from the sun (100 sq-ft=9.29sq-m corresponding to 13kW(17.4hp) maximum sun power). Also, the solar vehicle will not be operated exclusively at high noon on a clear day in the tropics which suggests additional energy storage needs. Now, all this energy storage suggests lots of batteries and/or capacitors or ?, which threatens our size/mass assumptions, but we're assuming magic technology so let's dismiss that concern.

So we'll consider only steady state, level ground, windless conditions; what will that 17hp from the Sun do for us? Given the vehicle assumptions above, it will sustain a maximum cruising speed of about 57mph. If we were to attempt to keep up with 70mph traffic, we would need about 50% MORE power! In reality, we must operate at lesser average speeds in order to return to storage the energy required to accelerate to our steady state speed, otherwise we must have another source of power to suplement solar energy, in which case, we don't have a solar car, we have a solar/? hybrid.

Consider further that to capture the entire 17hp available at high noon at the equator on the equinox, the entire 100sq-ft plan area must be perpindicular to the Sun, which suggests a flat topped vehicle! Imagine what that will do to aerodynamics and to the 0.32cd assumption, not to mention vehicle stability and the effect of crosswinds (its a good thing that we can't go very fast). And what does one do when the sun is not directly overhead, reducing the projected plan area, increasing the atmospheric path, increasing the angle of incidence (and hence reflection), or when the Sun is obscured?

The bottom line is that a solar powered vehicle that even remotely approximates our present day vehicles IS NOT POSSIBLE, no matter what technological advances occur. 1.4kW/sq-M is all the Sun has to offer on a good day! For solar cars to be viable, we would need a bigger (or closer) sun, in which case gasoline would be an inconsequential concern.

The bottom line is that a solar powered vehicle that even remotely approximates our present day vehicles IS NOT POSSIBLE

That was good information. Hopefully you would make it home before sundown in your solar car. Solar panels are useful just not for large amounts of energy in small areas. Plus their life expectancy is not long enough to pay for the energy they generate.

OK, I am by no means an expert, but I do understand that there are more sources of natural energy than just the sun. After all, just the movement of the car is a type of energy. After considering it all, you could create a vehicle that taps into Solar Power, Wind Power, and Kinetic Energy to regain some of the power that is often lost in conversion. Consider having some port-holes near the bottom of the vehicle that allow wind caused by vehicle motion to strike a turbine to produce additional energy. It may not refuel the car, but it can certainly increase power. How about two extra wheels that lightly touch the ground below the vehicle that also have light turbines in them to recover kinetic energy from the vehicle's motion.

These are all ideas, and by no means do I have a scientific mind to accompany them, but perhaps some of the energy converted into motion can be recovered to one degree or another.

Everyone has good points. Practical solutions will require out of the box thinking:

Solar augmented Hybrid SUVs They already have large semi-flat roofs, motors, gas backup. Solar would simply augment the charging, requiring less gas over time. Vehicles don't usually travel more than 1 or 2 hours a day. They will keep charging the rest of the time, so long as they are parked in sunlight.

Houses with solar panels could charge battery packs that are automatically swapped out when the vehicle is parked in the owners garage. Solar "roofed" parking lots could also swap out standard packs in some automated way. Maybe they'll be interchangeable with more expensive hydrogen fuel cell power packs, for those longer trips.

Perhaps that mass of asphalt called a street could somehow end up charging interchangeable battery packs for the populous. All that surface area... hmm, maybe there's a way to turn it all into a big collector with new materials and technology.

Solar won't do it all, but it can be a contributor. An electric motor vehicle manufacturing infrastructure is already well on its way. Hybrids and hydrogen will see to that. We might as well work all angles as a society to optimize it.

Solar needs full sun at the correct angle so it's best used in a fixed location like a house. Solar vehicles are electric vehicles, that are charged and running from the solar panels. The best is a very efficient EV like the T-Zero from AC Propulsions and good solar panels at home from Sunpower at 20% efficiency. Together , but not at the same location you have a winning combination. Or you can suck gas thats 60% imported and making Exxon rich so they make more oil spills and kill our trade deficit and fund terrorist. It's your choice. I installed grid ties solar, live efficiently and ride a bicycle to work for health and the environment. I make my choices EVeryday.

Here is a company that lists their installed products. Note that in CA you get a big rebate on the installation. The average installed price is about $20k. Pay off in 12 years. The panels are warranted by the manufacturer for 25 years. That is a big improvement from the system I put on my home in AZ. It lasted a little over 4 years and the company was out of business. The interest on $20,000 would pay my electric bill.

I would only consider solar if I was in Hawaii. Some areas do not have commercial power. And those that do are very expensive. My bill on a house I own in Hilo averages $480 per month with No air conditioning or heat. Just cooking, lights and hot water. There I could probably recoup the cost.

I put grid tied solar on my home in AZ in 2001 with no incentives or net-metering. In 2004 I petitioned SRP and we all now have net-metering. My system has worked perfect. I installed it myself and save 100 a month and only paid 12K. I have solar screens to block heat in summer , 2 solar tube lights, energy star Lennox heat pump at 16.5 SEER, efficient fridge from Sears, Compact florescent lights and even use a solar over a lot. What happened to your system ?, maybe I can fix it for you for free. There are super companies now in AZ to install and do all paperwork for State,FED and Util incentives. Call American Solar in Scottsdale, they are the best. JIM

The home is in Havasu. I sold it in 1987. Back then the warranty was 5 years. The manufacturer did not stay in business that long. I guess I was ahead of the curve. I was trying to cut my $280 per month electric bill.